Wireless moisture measurement for the roll coatings of fiber web machines and measuring equipment

ABSTRACT

The various embodiments of the invention are connected to a radio-frequency identifier of the roll coating in a fiber web machine. The fiber web machine comprises a radio-frequency identifier (for example RFID, RFID-tag), so that the moisture content can be measured from the roll or from the roll coating of a fiber web machine.

FIELD OF THE INVENTION

The invention relates to measuring moisture in a fiber web machine. More precisely, the invention relates to measuring moisture in a coated roll wirelessly, particularly by utilizing a radio-frequency identifier.

BACKGROUND OF THE INVENTION

Modern fiber web machines, such as paper, board, tissue and finishing machines or their sub-units often include rolls that are coated by a polymer material. Among the most common coating materials are epoxy, rubber, polyurethane and fiber-reinforced polymer coatings, i.e. composite coatings. It is a well-known feature of many polymer-based roll coatings that as porous materials, they absorb moisture in the papermaking process when functioning as part of the process. This is not harmful for the process, but it must be taken into account in the roll coating construction in order to prevent moisture from accessing the roll frame, where it causes corrosion and finally results in the destruction of the roll coating, which are apparent problems. Particularly problematic coatings with respect to moisture absorption are polyurethane coatings, and to some extent also epoxy coatings, especially their fiber-reinforced varieties.

Apart from using moisture protection, it has been known to give the users of the machines position-specific instructions for drying polyurethane coated rolls at regular intervals, in order to prevent moisture from penetrating into the roll coating. These recommendations are based on laboratory tests, where said materials are first subjected to moisture, whereafter their weight is measured before and after oven treatment, where the test pieces are again dried. However, laboratory tests have not given a particularly clear image of the proceeding of moisture in the material, and consequently the defining of working and drying times in a paper machine is only based on indicative background information. In practice, the rolls are taken out of the machine at roughly one year intervals in order to prevent moisture from proceeding to the glue layer provided in between the roll frame and the roll coating. Therefore the situation often leads to unnecessary stoppages and roll replacements. It would be desirable to find a reliable way of defining moisture in the coating, which also would help in optimizing the running of the machine and the production.

SUMMARY OF THE INVENTION

The object of the invention is a more precise way of defining moisture in the coating of a roll.

According to an aspect of the invention, there is realized a fiber web machine that comprises a radio-frequency identifier, so that moisture can be measured from roll or from roll coating of the fiber web machine.

According to another aspect of the invention, there is realized a fiber web machine roll that comprises a roll frame and a polymer coating on the frame, the roll including means for measuring moisture wirelessly from the roll or from the roll coating.

According to another aspect of the invention, there is realized a method for measuring moisture from a coating of a roll in a fiber web machine, in which method data from the roll or from the roll coating is received wirelessly for defining the moisture content.

According to another aspect of the invention, there is realized a method for defining moisture from a coating of a roll in a fiber web machine, in which method data from the roll or from the roll coating is transmitted wirelessly, said data indicating the moisture of the roll coating or the roll.

By means of various alternative embodiments of the invention, it would be possible to observe the moisture and its proceeding in the roll coating in a reliable and precise manner. Advantageously the roll can thus be utilized better than in the prior art. From the roll, it can be read or otherwise detected when it needs drying. In addition, the drying times can be optimized. Also the number of cases where the roll is broken due to corrosion in the roll frame can be remarkably reduced, and at best completely eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below, by way of exemplary embodiments only, with reference to the appended drawings, where:

FIG. 1 is a schematical illustration describing a roll in a fiber web machine provided with roll coating; radio-frequency remote identifiers are also illustrated according to an embodiment of the invention,

FIG. 2 is a cross-sectional illustration of a roll, where both the roll coating and the radio-frequency remote identifiers are visible according to embodiments of the invention, and

FIG. 3 illustrates an example of the layout of a radio-frequency remote identifier.

EXAMPLES OF VARIOUS EMBODIMENTS OF THE INVENTION

Thus, the invention is described below with reference to exemplary embodiments only. The various embodiments of the invention are connected to a fiber web machine. The fiber web machine comprises, i.e. includes, a radio-frequency identifier in the roll coating of a fiber web machine, or in the vicinity of said coating. In some examples, the radio-frequency identifier is an RFID tag that measures or transmits the moisture content in the roll coating or in the vicinity of the roll coating. In addition to the above description, the various embodiments of the invention can contain many different additional features or properties.

FIG. 1 illustrates one of the numerous embodiments of the invention. The schematical illustration shows a fiber web machine roll 100 comprising a roll frame and either a penetrating axle or axle stubs, both of which are referred to by the reference number 103. The roll frame 103 can be made of metal, such as cast iron or steel, or of fiber reinforced plastic composite. The roll 100 is provided with a roll coating 101. The roll coating can be for example polyurethane, and typically it is connected to the roll frame 100 by a glue layer or another adhesive layer. A radio-frequency identifier 104 is in FIG. 1 shown as enlarged. The radio-frequency identifier 104 is located for example on the boundary surface of the roll coating 101 and the roll 100. The remote identifier 104 can also be placed in the roll coating, in the roll 100 or in the vicinity thereof. Several radio-frequency identifiers 104 can be placed in the roll coating, in the vicinity thereof and on the roll, so that the moisture in the roll, in the roll frame and/or in the roll coating 101 can be detected. In the example of FIG. 1, there are shown three radio-frequency remote identifiers 104. This is only an illustrative example, and the number of radio-frequency identifiers can vary from one up to a considerable number.

FIG. 2 illustrates an embodiment of the invention in a cross-sectional image of the roll 100. The roll coating 101 and the radio-frequency identifiers 104 are visible according to an embodiment of the invention. FIG. 2 is an illustration in principle of the various different alternatives for placing the identifiers 104 of the example in the roll 100. The radio-frequency identifiers 104 can also be placed in a regular order on the roll 100. Further, the identifiers 104 can be placed in predetermined locations on the roll 100. It is advantageous to place the identifiers 104 in the roll 100 axially at several points, at different radial depths, in the roll coating 101 and on the boundary surface. In some embodiments of the invention, the radio-frequency identifier 104 can also be embedded in the roll frame. Now the roll frame can be made for example of fiber reinforced composite or a corresponding material.

In an embodiment of the invention, on the boundary surfaces of the roll coating 101 (for example on the boundary surface of the roll frame and the coating or of the roll coating and air, etc.) or in the coating 101, there are installed radio-frequency identifiers 104, for instance RDIF-tags. In the first step, the radio-frequency identifiers 104 react to moisture by switching off their operation, when the percentage of moisture surpasses a given value, for instance when the percentage of moisture grows too high. Consequently, by reading the radio-frequency identifiers 104, it is easy to observe the proceeding of moisture in the structure, respectively in the roll 100, in the roll frame 102 and in the coating 101. Hence the moisture properties of the roll 100 and the roll coating 101 can be measured and defined, even at a distance. Respectively roll-specific and/or position-specific working and/or drying times can be defined for the roll 100. Advantageously the radio-frequency identifier 104 or tag is thus arranged to function as a moisture fuse.

In an embodiment of the invention, the radio-frequency identifier 104, for example an RFID tag, includes or comprises an integrated moisture sensor. Thus it is possible to make use of moisture sensoring features integrated in radio-frequency identifiers, which also are capable of generating sensor data of the moisture content from their integration depth.

On the other hand, an embodiment of the invention is connected to the reading technique of a radio-frequency identifier 104, where a radio-frequency identifier 104 is used as a transfer path or transfer medium. For instance the RFID reading technique is used so that RFID reading standards are employed as a transfer path for sensor data. Now in the coating or in the vicinity thereof, for instance on the boundary surfaces of the roll coating, there is provided a separate moisture detector (alternatively called moisture sensor). The moisture detector (not illustrated) is connected to a radio-frequency identifier 104. Now the moisture data obtained from the detector can be transmitted by means of the radio-frequency identifier. The applied transmission protocol is for example the NFC transmission protocol, which is an expanded 13.56 MHz RFID standard.

In the various embodiments of the invention, the radio-frequency identifier 104, for example an RFID tag or an RFID identifier, is thus arranged to indicate the moisture of the roll coating. Radio-frequency identification, i.e. for instance RFID (Radio frequency identification), is a method for reading and recording of data by using RFID identifiers. An RFID identifier is a small device that can be included in the product in the manufacturing step, for instance in connection with the casting of the coating, or it can be attached thereto afterwards, for instance with glue or adhesive tape, etc. RFID identifiers include an antenna in order to be able to transmit and receive radio-frequency requests to and from an RFID transceiver. RFID identifiers can be active, passive or semi-passive.

Passive RFID identifiers do not have their own power source. The extremely low electric current required for the use of the device is induced by the radio-frequency scanning received in the antenna, by which scanning the identifier is capable of sending a response. Owing to power and price requirements, the response of a passive RFID identifier is short, typically an ID number. Because the device lacks its own power source, it is made fairly small: for example, an RFID can be placed even under the skin, having a size of for example 0.4 mm×0.4 mm, and being thinner than a sheet of paper, i.e. in practice nearly invisible. The reading ranges of passive identifiers vary between 0 mm and 5 meters.

A semi-passive RFID identifier includes a power source but does not have an active transmitter. However, the own power source results in a larger operational range than with a passive identifier and enables a wider functionality, including the storage of data in the specific memory (ROM, WORM) of the identifier.

As for active RFID identifiers, they include a power source, and they can have a longer range and a bigger memory than passive identifiers. They can also record additional data sent by a transceiver. At present, the smallest active RFID identifiers are more or less of the same size as a coin, but thinner. With many active identifiers, their reading ranges are tens of meters, and their battery life extends to several years.

A radio-frequency identifier is an advantageous and cost-effective method for measuring moisture from the coating of a fiber web machine roll. Wirelessness constitutes a particular advantage in those positions of a fiber web machine where the roll surface is subjected to stronger wet exposure, for instance in the suction, control and lead rollers of the wire element or the press, or at the coating/web sizing station, but is also handy in the conditions of the dry end of the machine, where the roll may be exposed to steam.

In a radio-frequency identifier, for example an RFID identifier, for example the following radio frequency areas can be used: high-frequency identifiers (13.56 MHz), UHF identifiers (868-956 MHz) and microwave identifiers (2.45 GHz) or higher frequencies.

Ramifications and Scope of the Invention

Although the above specification brings forth many details, they are only presented in order to illustrate the invention, and should therefore not restrict the scope, of the invention. It is pointed out that many details can be combined in numerous ways in one or several embodiments of the invention, i.e. it is obvious for a man skilled in the art that many modifications and variations can be made in the equipment without departing from the characterizing features or spirit of the invention. 

1. A fiber web machine, the fiber web machine comprising a radio-frequency identifier, so that moisture can be measured from roll or roll coating of the fiber web machine.
 2. A fiber web machine according to claim 1, wherein the radio-frequency identifier is placed in the coating of the fiber web machine roll or in the vicinity of said coating.
 3. A fiber web machine according to claim 1, wherein the radio-frequency identifier is placed on boundary surface of the roll coating.
 4. A fiber web machine according to claim 1, the fiber web machine further comprising several radio-frequency identifiers in the coating of the roll or in the vicinity of said coating.
 5. A fiber web machine according to claim 1, wherein the radio-frequency identifier comprises an RFID device.
 6. A fiber web machine according to claim 1, wherein the fiber web machine comprises the radio-frequency identifier, so that moisture can be defined either roll-specifically or location-specifically.
 7. A fiber web machine according to claim 1, wherein the radio-frequency identifier has a determined location, so that moisture can be defined location-specifically from the roll or from the roll coating.
 8. A fiber web machine according to claim 1, the fiber web machine further comprising means for defining the drying time and location on a basis of the measured moisture data.
 9. A fiber web machine according to claim 1, wherein the radio-frequency identifier includes an integrated moisture sensor.
 10. A fiber web machine according to claim 1, wherein the radio-frequency identifier is arranged to be connected to a moisture detector, so that the radio-frequency identifier transmits data obtained from the moisture detector.
 11. A fiber web machine according to claim 1, wherein the radio-frequency identifier is arranged to be switched on or off, in case the moisture content in the vicinity of the radio-frequency identifier exceeds a given threshold value.
 12. A roll of a fiber web machine, comprising a roll frame and on top of the roll frame, a coating made of polymer material, wherein the roll comprises means for measuring moisture wirelessly from the roll or from the roll coating.
 13. A roll according to claim 12, wherein said means comprise a radio-frequency identifier that is placed in the coating of the fiber web machine roll or in the vicinity of said coating.
 14. A roll according to claim 12, wherein the radio-frequency identifier is placed on a boundary surface of the roll coating and the roll frame.
 15. A roll according to claim 12, the roll further comprising several radio-frequency identifiers located in the coating of the roll or in the vicinity thereof.
 16. A roll according to claim 12, wherein the radio-frequency identifier comprises an RFID device.
 17. A roll according to claim 12, the roll further comprising a radio-frequency identifier, so that moisture can be defined either roll-specifically or location-specifically.
 18. A roll according to claim 12, wherein the radio-frequency identifier has a defined place of location, so that moisture can be defined location-specifically from the roll or from the roll coating.
 19. A roll according to claim 12, wherein the radio-frequency identifier includes an integrated moisture sensor.
 20. A roll according to claim 12, wherein the radio-frequency identifier is arranged to be connected to a moisture detector, so that the radio-frequency identifier transmits the data obtained from the moisture detector.
 21. A roll according to claim 12, wherein the radio-frequency identifier is arranged to be switched on or off, in case the moisture content in the vicinity of the radio-frequency identifier exceeds a given threshold value.
 22. A method for measuring moisture in the coating of the fiber web machine roll or in the vicinity of said coating, comprising: utilizing the fiber web machine according to claim
 1. 23. A method for measuring moisture in a coating of a roll of a fiber web machine, in which: data is received wirelessly from the roll or from the roll coating for defining the moisture content.
 24. A method according to claim 23, wherein the received data further is analyzed, so that the moisture content in the roll and its respective position in the roll can be identified.
 25. A method according to claim 23, in which the received data also is displayed.
 26. A method for defining moisture in a coating of a roll of a fiber web machine roll, in which: data is transmitted wirelessly from the roll or from the roll coating, which data indicates the moisture content in the roll coating or in the roll.
 27. A method according to claim 26, wherein the wireless transmission of the data is performed according to a request.
 28. A method according to claim 26, wherein the wireless transmission of the data is performed in periodically.
 29. A method according to claim 26, wherein the data is transmitted to a machine control program in order to optimize a point of time of the drying process. 